SINGAPORE – To feel cooler on a hot day, set the air-conditioner at a higher temperature than you intended and also turn on the fan – doing this conserves energy, too.

The “hybrid cooling” solution was piloted at an office space in the Zero Energy Plus Building at the BCA Academy in Singapore.

Over 11 weeks, the office occupants were exposed to two indoor conditions – the office cooled to 26.5 deg C with ceiling fans running, and the space cooled to 24 deg C.

In the study published in 2023, they said that they found their comfort levels were similar in both scenarios.

As a bonus, the air-con plus fan method used 30 per cent less energy.

The pilot was led by the Berkeley Education Alliance for Research in Singapore.

One of its faculty members is Professor Stefano Schiavon, who highlighted the findings of the pilot in his lecture at the First Global Heat Health Information Network (GHHIN) South-east Asia Heat Health Forum on Jan 7.

He is professor of architecture and civil and environmental engineering at the University of California, Berkeley.

Using fans with air-con was one of numerous solutions that were discussed at the four-day conference, as heat health scientists, weather experts and policymakers convened to find ways to protect people living in a sweltering South-east Asia amid rising temperatures.

Other solutions discussed include setting up national heat action plans and promoting ground-up efforts that can help vulnerable communities and remote villages stay safe.

Taking lessons from the fan study, Prof Schiavon and Associate Professor Jason Lee from the NUS Yong Loo Lin School of Medicine are now tracking the sleep quality of construction workers in non-air-conditioned dormitories and residents in air-conditioned bedrooms.

With more nights expected to get warmer in Singapore amid climate change, this new project seeks to find ways to optimise people’s thermal comfort at night.

While climate change is causing global temperatures to rise, how each region experiences the heat differs. In South-east Asia, people are feeling chronically uncomfortable because the high humidity here prevents sweat from evaporating well.

Heat strain, particularly due to exertion in the scorching weather, is also a greater risk for outdoor workers and those of lower income levels. The region has about 96 million workers in the agriculture and farming sectors.

In 2023 and 2024, many South-east Asian regions were hit by severe heatwaves during the hotter months, with heat-related deaths reported in Indonesia, Malaysia, Thailand and the Philippines.

In May 2024, Laotian farmers grappled with lower yields of crops like coffee and vegetables.

While less visible than other problems, the dangers of heat are far more wide-ranging, including reduced productivity and economic loss, accidents at work and poorer mental health.

And yet, many countries’ responses to extreme heat are often not as advanced as for other disasters like typhoons, landslides and floods.

The recently launched South-east Asia Hub under the GHHIN – housed at the National University of Singapore Yong Loo Lin School of Medicine – aims to coordinate a regional response to rising heat.

The sweltering conditions in the region are also exacerbated by the development of cities and buildings, leading to the urban heat island effect as roads and buildings retain the sun’s heat.

This makes urban places much hotter than their surrounding rural areas.

Professor of urban climate Winston Chow of Singapore Management University noted that the urban heat island effect is stronger in Asian cities than in those in the Americas or Europe.

“The likely reason speaks to the rapid urbanisation in terms of population growth and development that has occurred within the East, South and South-east Asian cities.

“In Singapore, about 50 per cent of the increased temperature arises from urban development,” he said.

Prof Chow added that even the best designed and well-thought-out heat action plans or climate resilience plans require not just political will, but also financial resources and backing.

He noted that much of climate finance is still directed towards mitigation, that is, carbon emission reduction efforts. “More investments towards heat adaptation measures are sorely needed,” he said.

One point that was repeated throughout the Forum was the need to keep potential solutions to heat stress applicable across different countries and circumstances.

Professor Ollie Jay, a heat and health expert from the University of Sydney, emphasised that solutions have to be affordable and scalable, especially for those in the construction and agricultural sectors.

He said: “It’s important to keep in mind that the interventions that we test are widely applicable to the most vulnerable. Often, people really want to (look at) cool tech and fancy cooling vests. That’s completely useless to a large proportion of the population. The people who are most vulnerable to heat health impacts are often operating in pretty resource-scarce environments. So the interventions that we test are, by necessity, very simple and very low-resource.”

Prof Jay cited the use of fans, shade and misting as examples of simple, scalable interventions.

On the other hand, some solutions cannot be applied in all situations.

Prof Jay said fans can be a good cooling measure in a highly humid place up to 38 deg C. But in a hot, dry region at 45 deg C and above, fans triple the rate of overheating, he added.

Fans help sweat evaporate, providing relief. In dry conditions, a person does not sweat, and blowing hot air on the skin would make him feel hotter, increasing strain on the heart as well.

• The Straits Times is the media partner for the First GHHIN South-east Asia Heat Health Forum, held in Singapore from Jan 7 to 10, 2025.
• Shabana Begum is a correspondent, with a focus on environment and science, at The Straits Times.

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